| 摘要 |
PURPOSE:To eliminate the instability of firing at an ignition timing when a rotary burner is cooled and the instability of combustion following to said instability by controlling the number of revolutions of a burner fan motor so as to forward an air flow rate lower than a proper air flow rate to the quantity of fuel fed by a fixed quantity on the ignition and combustion of the burner. CONSTITUTION:A first fan motor revolutional number setting circuit 2 receives a prepurge signal, and sets and outputs the revolutional number voltage VA of a burner fan motor so that the burner fan motor generates an air flow rate lower than a proper air flow rate to the flow rate of fuel fed to a burner at the initial stage of igniton by a fixed quantity. The input voltage of a fan motor control circuit 7 smoothly rises by the function of a time constant circuit 6 after a time t2, and the output voltage VB of a second fan motor setting circuit 4 is received. Since the combustion of the burner is started at a time t1, the fan motor is driven by the number of revolutions lower than that giving the proper air flow rate corresponding to the quantity of fuel fed for the times t1-t2, and an air flow rate is reduced. |
